Final answer:
House ventilation systems, particularly large windows or openings close to the ground or accessible from outside, should be secured with steel bars. This safety measure, mandated by building codes in MDCs, protects inhabitants while maintaining airflow.
Step-by-step explanation:
The subject of this question pertains to house ventilation systems and safety measures related to their construction, which falls within the field of Engineering. Specifically, this question deals with the need for steel bars to secure house ventilation systems as part of the safety requirements set out in building codes in many More Developed Countries (MDCs).
In many MDCs, building codes mandate safety features that homes must include. This is to ensure that all houses are safe for inhabitants. Requirements can include running water, working ventilation and heating systems, structural integrity, smoke detectors, and proper electrical wiring.
To specifically answer the student's query: Ventilation systems, such as large windows or other openings that can be accessible from outside, should be secured with steel bars or grills to prevent unauthorized entry while still allowing airflow. This is especially crucial on ground floors or any accessible points where intrusion is possible.